JP5829527B2 - Reactor water level and temperature measurement device - Google Patents

Description

  The present invention relates to a reactor water level and temperature measuring device for measuring a reactor water level and temperature.

  In a boiling water reactor, cooling water is evaporated in the reactor by heat generated in the core fuel, and the turbine is rotated by the generated steam to generate electricity. Therefore, a reactor water level that is a boundary between cooling water and steam is formed in the upper part of the core. The reactor water level is controlled at an appropriate position in order to ensure the performance of a steam / water separator that separates steam and cooling water. In the event of an accident such as loss of cooling water, the water level is monitored so that the core is not exposed to the cooling water and heat removal is insufficient, and an emergency cooling device is activated as necessary.

  Conventionally, the water level in a boiling water reactor is that the pressure from the reference height water column and the pressure corresponding to the water level in the reactor are led to the differential pressure transmitter outside the reactor by instrumentation piping, and output from this differential pressure transmitter. It is measured based on the differential pressure signal. A plurality of types of instrumentation pipes and differential pressure transmitters used for measurement are provided depending on the application. For example, in addition to the normal level water level meter that closely monitors a narrow range in order to keep the cooling water and steam separation performance high, there is a water level meter that covers a wide range to operate the safety function during a transient or accident. is set up.

  On the other hand, from the viewpoint of improving responsiveness of water level measurement and ensuring diversity, a method for detecting the reactor water level directly in the reactor has been studied, and a water level meter using a thermocouple has been proposed.

  First, monitoring of the reactor core that detects the position of the water surface by incorporating a sheath thermocouple into the neutron detection pipe of the boiling water reactor and generating a temperature difference above and below the water surface An apparatus is known (see, for example, Patent Document 1).

  Second, a thermocouple water level monitoring device for monitoring the water level in the upper plenum of a pressurized water reactor vessel is disclosed, although it is not intended for diversification of boiling water reactor water level gauges. Has been. This apparatus is known to include a storage tube, a plurality of water level detector guide tubes in the storage tube, and a water level detector inserted through each guide tube (see, for example, Patent Document 2). Here, the water level detector includes a thermocouple forming a cold junction and a hot junction and a heating wire provided adjacent to the hot junction. Each guide tube is supported on the storage tube by a drip prevention plate, and the storage tube is provided with a bubble separation part at the lower part thereof to prevent mixing of bubbles.

JP 59-112290 A JP-A-8-220284

  The water level gauge using the thermocouple as shown in Patent Documents 1 and 2 above can be diversified and multiplexed by combining it with a conventional boiling water reactor water level gauge using a differential pressure transmitter. This can greatly reduce the possibility of measurement being impossible.

  However, simply combining a water level meter using a thermocouple with a conventional water level meter makes it difficult to determine which one is correct if one of them fails. It cannot be improved. In order to improve the reliability of the indicated value, it is important to evaluate the soundness of the measurement system including the sensor and the signal transmission path and to confirm that the indicated value is reliable.

  It is also effective to improve the reliability of the indicated value to reduce the possibility that the water level gauge detection system itself using a thermocouple will break down or break.

  Therefore, an object of the present invention is to provide a reactor water level and temperature measurement device that can evaluate the soundness of a detection unit and a signal transmission unit using a thermocouple and confirm the reliability of an indicated value. . It is another object of the present invention to provide a highly reliable reactor water level and temperature measurement device that can reduce the damage and failure of a detection unit using a thermocouple.

  In order to achieve the above object, the present invention provides a reactor water level and temperature measuring device that detects the reactor water level from the temperature measured by the thermocouple by installing a plurality of thermocouples inside the pressure vessel of the reactor. An in-core instrumentation housing welded to the bottom of the vessel, an in-core instrumentation guide tube disposed between the upper part of the in-core instrumentation housing and the core support plate, the in-core instrumentation housing and the in-core instrumentation guide pipe In-reactor instrumentation tube to be inserted into the reactor, a water level and temperature detection sensor comprising thermocouples and heater wires installed at multiple heights inside the in-reactor instrumentation tube, and a temperature measurement device for measuring the temperature of the thermocouple , A heater control device for controlling the current to the heater wire, and a memory storing a threshold table for associating the thermocouple temperature before the heater energization and the thermocouple temperature rise when the heater is energized with the steam atmosphere, water atmosphere, and sensor failure Device and temperature measuring device Apply the measured thermocouple temperature before energizing the heater and the amount of temperature rise when energizing the heater to the threshold table, whether the water level and temperature detection sensor is in a steam atmosphere, water atmosphere, or sensor failure A water level / temperature / failure determination device that generates information on the water level, temperature, and sensor failure in the reactor based on these data, and a display device that displays the water level, temperature, and failure information It is intended to provide.

  As another example, in the reactor water level and temperature measurement device that detects the reactor water level from the temperature measured by the thermocouple by installing multiple thermocouples inside the reactor pressure vessel, welding is performed on the bottom of the pressure vessel. Inserted into the in-core instrumentation housing, the in-core instrumentation guide tube disposed between the upper part of the in-core instrument housing and the core support plate, the in-core instrument housing and the in-core instrumentation guide pipe, Water level and temperature detection with an in-core instrumentation tube located adjacent to or outside the outermost periphery fuel of the reactor, and thermocouples installed at multiple heights inside the in-core instrumentation tube Sensor, temperature measuring device that measures the temperature of the thermocouple, and whether the surroundings of the water level and temperature detection sensor are in a steam atmosphere, a water atmosphere, or a sensor failure based on the thermocouple temperature Based on these data, And the water level, temperature, failure determination device for generating a water level and temperature, water level, is obtained as comprising a display device for displaying temperature, the failure information.

According to the present invention, it is possible to provide a reactor water level and in-reactor temperature measurement device capable of evaluating the soundness of a detection unit and a signal transmission unit using a thermocouple and confirming the reliability of an indicated value. it can. In addition, it is possible to provide a highly reliable reactor water level and in-reactor temperature measurement device that can reduce the damage and failure of the detection unit using a thermocouple. By these, the indicated value reliability of the reactor water level and temperature measuring device can be improved.

1 is a conceptual diagram illustrating a system configuration of Embodiment 1. FIG. It is a cross-sectional view of a nuclear reactor core. It is a structural diagram of a water level and temperature detection sensor. It is a structural diagram of a water level and temperature detection sensor. It is a measurement flowchart of a water level and temperature. It is explanatory drawing of an electric current pattern. It is explanatory drawing of a threshold value table. It is explanatory drawing of a threshold value table. It is explanatory drawing of the flow stop of a water level and a temperature detection sensor. It is explanatory drawing of the flow stop of a water level and a temperature detection sensor. It is explanatory drawing of the flow stop of a water level and a temperature detection sensor. It is explanatory drawing of the example of attachment of a flow stop. It is explanatory drawing of the example of attachment of a flow stop. It is explanatory drawing of the example of a display of a water level and its time series data. It is a measurement flowchart of the water level and temperature of Example 2. It is explanatory drawing of the example of the heater current control in Example 2. FIG. It is a measurement flowchart of the water level and temperature of Example 3. FIG. 10 is a conceptual diagram illustrating a system configuration of a fourth embodiment. It is a block diagram of the resistance measuring apparatus of Example 4. FIG. 6 is a transverse cross-sectional view of a nuclear reactor core according to a fifth embodiment. FIG. 6 is a transverse cross-sectional view of a reactor core according to a sixth embodiment. It is explanatory drawing of the example of a display of the three-dimensional temperature distribution in the reactor pressure vessel of Example 6. FIG.

  Hereinafter, examples will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram showing the system configuration of the first embodiment.

  A reactor core 3 surrounded by a shroud 2 is installed inside the reactor pressure vessel 1, and a large number of fuel assemblies (not shown) in the reactor core 3 are supported by the reactor core support plate 4 and the upper lattice plate 5. Yes. A plurality of water level and temperature detection sensors 6 are installed at different height positions in a plurality of (only two bodies are shown in FIG. 1) inserted in the core 3. The lower part of the in-core instrumentation tube 7 is inserted into an in-core instrument housing 8 and an in-core instrumentation guide tube 9 attached to the lower part of the reactor pressure vessel 1, and the upper part is fixed to the upper grid plate 5. Has been. The in-core instrument housing 8 and the in-core instrument tube 7 are provided with water inlets 10, 11, and 12. The water inlets 10 and 11 are installed below the water level and temperature detection sensor 6, and the water inlet 12 is installed near the upper end of the in-reactor instrumentation pipe 7, and the reactor water level drops below the upper grid plate 5. In addition, the cooling water 13 communicates so that the water level in the in-core instrumentation tube 7 and the reactor water level coincide. A stop cock 14 is attached below the water inlet 11 inside the in-core instrumentation tube 7 so that the coolant 13 does not leak from the lower end of the in-core instrumentation pipe 7. A signal cable and a heater cable 15 are connected to the water level and temperature detection sensor 6, guided from the lower end of the in-core instrumentation pipe 7 to the outside of the reactor pressure vessel 1, and sent to the temperature measuring device 16 and the heater control device 17. It is connected.

  A conventional water level gauge using a differential pressure transmitter is instrumented from the pressure of a reference water column having a constant height formed in an instrumentation pipe connected downward by a steam condenser 38 and from the outside of the shroud 2 of the reactor pressure vessel 1. The differential pressure transmitter 39 and 40 measure the differential pressure from the reactor water pressure drawn by piping. In the reference water, the steam reaching the upper part of the reactor pressure vessel 1 via the steam / water separator 36 and the steam dryer 37 is cooled by the steam condenser 38 so that the water level is always kept constant. It is a mechanism to do. The water level and temperature measuring device of the present embodiment has a measuring range overlapping in the region of the conventional water level gauge and the core 3, and the water level is continuously measured from the top to the bottom of the reactor pressure vessel 1 by the combination of both. Can do.

  FIG. 2 shows a cross-sectional view of the reactor pressure vessel 1 at the core 3 portion.

  Although only two in-core instrument tubes 7 are shown in FIG. 1, as shown in FIG. 2, eight or more in-core instrument tubes 7 may be inserted into the gap of the fuel assembly 41. it can. By using a large number of in-core instrumentation tubes 7 and disposing the water level and the installation height of the temperature detection sensor so as to interpolate each other with respect to each in-core instrumentation tube 7, the water level can be adjusted at finer intervals. It can be detected. For example, as shown in FIG. 2, the in-core instrument tube 7 is divided into a first group, a second group, and a third group, and the water level and temperature inside the in-core instrument tube 7 belonging to each group. It is possible to detect a finer water level by shifting the height of the detection sensor 6 and determining one water level for each group (for example, one water level is determined by four for the first group). Become. In addition, as shown in FIG. 1, it is also possible to accommodate in the existing in-core instrumentation tube which accommodated the neutron detector 34 and the scanning neutron detector guide tube 35. FIG.

  FIG. 3 shows the structure of the water level and temperature detection sensor 6. FIG. 3 shows four water levels and temperature detection sensors 6d to 6g. Since the structures are the same, 6d will be described below.

  Inside the water level and temperature detection sensor 6d are a thermocouple 24d joined with a + side strand 22d and a -type strand 23d, a heater wire 25d for heating the vicinity of the thermocouple 24d, and heater lead wires 26d and 27d. Is stored. As the thermocouple 24d, a widely used K-type or N-type thermocouple can be used. Further, a nickel-chromium alloy high resistance wire or the like is suitable as the heater wire 25d. The heater lead wires 26d and 27d can suppress a voltage required for the heater power supply by using a wire having a relatively small resistance such as a copper wire or a nickel wire. The thermocouple and the heater are electrically insulated by an insulating material 28 such as alumina and stored in a sheath 21 made of stainless steel or the like. The + side strand 22d, the − side strand 23d, the heater lead wire 26d, and 27d are connected to the signal cable and the heater cable 15 via the connector 29. The + side strand 22 d and the − side strand 23 d are connected to the temperature measuring device 16, and the heater lead wires 26 d and 27 d are connected to the heater control device 17.

  FIG. 4 shows another example of the structure of the water level and temperature detection sensor 6.

  In this example, the heater wire 25 is shared, and four thermocouples 24h to 24k are accommodated in the same sheath 21 made of stainless steel or the like. The + side strands 22 h to 22 k and the − side strands 23 h to 23 k are connected to the temperature measuring device 16, and the heater lead wires 26 and 27 are connected to the heater control device 17.

  As shown in FIG. 1, the temperature measurement device 16 and the heater control device 17 are connected to a water level / temperature / failure determination device 18, and the water level / temperature / failure determination device 18 displays a threshold table storage storage device 19. A device 20 is provided.

  Next, the operation of the reactor water level and temperature measuring apparatus shown in FIGS. 1 to 4 will be described with reference to FIG. FIG. 5 shows a measurement flow of the reactor water level and temperature. The measurement of the water level and temperature starts periodically from the water level / temperature / failure determination device 18.

  The water level / temperature / failure determination device 18 collects data necessary for determination of the water level / temperature / failure by repeating the following control for all the water levels and the temperature detection sensors 6 according to a predetermined order. (Step S10).

  First, a temperature data collection command before energization of the target sensor 6 is output to the temperature measuring device 16. The temperature measurement device 16 that has received the collection command inputs an output signal from the target sensor and sends it to the water level / temperature / failure determination device 18. The water level / temperature / failure determination device 18 stores the received temperature data from the sensor in a storage device (not shown) (steps S20 and S30).

  Next, a command is output to the heater control device 17 to energize the heater wire 25 of the target sensor 6. The heater control device 17 energizes the heater wire 25 according to the built-in current pattern (step S40). As the current pattern, a pattern as shown in FIG. 6 can be used. When a current flows through the heater wire 25, the ambient temperature of the heater wire 25 of the target sensor 6 rises due to Joule heat. Then, after energization for a preset time, the water level / temperature / failure determination device 18 outputs a temperature data collection command during energization to the temperature measurement device 16. The temperature measurement device 16 that has received this command inputs an output signal from the target sensor and sends it to the water level / temperature / failure determination device 18 (step S50). The water level / temperature / failure determination device 18 stores the received temperature data from the sensor in a storage device (not shown) and simultaneously outputs a command to stop energization according to the built-in current pattern to the heater control device 17 (step S60). . Next, the water level / temperature / failure determination device 18 stores whether the surroundings of the individual water levels and the temperature detection sensors 6 are in a steam atmosphere, a water atmosphere, or whether the sensor has failed according to the collected temperature data. It judges with the threshold value table which is stored in 19 (step S70). By repeating the above control for all the water level and temperature detection sensors 6, the collection of data necessary for determination is completed.

  FIG. 7 shows an example of the threshold table.

  The threshold value table is a table of threshold values for determining the steam atmosphere and water atmosphere and the threshold values for determining the water atmosphere and failure according to the temperature rise (Δ ° C.) when the heater is energized for each temperature (° C.) before heater energization Has been. Since the absolute value of the threshold value changes depending on the water level and the structure of the temperature detection sensor 6 and the amount of current supplied to the heater, it is not shown in FIG. 7, but the thermal conductivity of the steam increases as the temperature rises. The threshold for determining the atmosphere and the water atmosphere decreases with increasing temperature. In addition, the thermal conductivity of water increases with increasing temperature, but the ratio is smaller than that of steam, and the threshold value decreases slightly with increasing temperature. When the temperature of the cooling water 13 approaches the critical temperature of 374 ° C., the amount of increase in temperature of the steam atmosphere and the water atmosphere approaches, making determination difficult. In this example, 310 ° C. or higher is not determined.

  FIG. 8 shows another example of the threshold table. Although the table is almost the same as that in FIG. 7, a boundary region is set between the steam atmosphere and the water atmosphere. When the temperature rise amount corresponding to this boundary region is collected, it is determined that a water level exists in the vicinity of the sensor.

  FIG. 9 shows the configuration of the water level and temperature detection sensor 6 that reduces the influence of the flow, in order to apply the determination of the steam atmosphere and the water atmosphere based on the threshold value when there is a coolant flow.

  The vicinity of the tip where the heater wire 25 of the water level and temperature detection sensor 6 is installed is covered with a flow stop 30, and the outside cooling water 13 enters the flow stop inside by the water flow port 31 provided on the surface. The flow itself is structured to be suppressed. The flow stop 30 allows the threshold table shown in FIGS. 7 and 8 to be used even when there is a coolant flow.

  10 and 11 show another example of the flow stop.

  In FIG. 10, an opening 32 is provided for taking the cooling water 13 into the flow stop. Moreover, in FIG. 11, the flow stop 30 is comprised combining the disk which suppresses a flow.

  As shown in FIGS. 9 to 11, such a flow stop is provided inside the existing in-core instrument tube 7 as shown in FIG. 12 in addition to the method of fixing to the water level and temperature detection sensor 6. It can also be fixed to the scanning neutron detector guide tube 35 provided through a weld 33. Alternatively, as shown in FIG. 13, the inside of the in-core instrument tube 7 can be fixed via a welded portion 33.

  In this way, the results determined for the individual water level and temperature detection sensors 6 are arranged in order of installation height for each group shown in FIG. 2 by the water level / temperature / failure determination device 18. Then, the intermediate height between the height of the sensor installed at the lowest position among the sensors in the vapor atmosphere and the height of the sensor installed at the highest position among the sensors in the water atmosphere is determined as the water level height ( Step S80).

  Or when there exists a sensor determined to be a boundary area, the installation height of the sensor is determined as a water level height. When there is a contradiction in the judgment results of the sensors in the group, for example, when the sensor at a higher installation position than the sensor judged as the steam atmosphere is judged as the water atmosphere, or when the temperature before energization is outside the judgment area In some cases, it is determined that the water level is unknown. The water level can be determined by the above procedure. The determined water level is stored as time-series data in a memory (not shown) and displayed by the display device 20 (step S90).

  FIG. 14 shows an example of a display screen for the water level measurement value.

  FIG. 14 shows an example in which four in-core instrumentation tubes 7 are assigned to three sensor groups, and four water level and temperature detection sensors 6 are installed in one in-core instrumentation tube 7. ing. Each in-core instrumentation tube 7 is indicated by a vertical bar, and the radial installation position in the furnace is indicated below the vertical bar (for example, 12-14). The horizontal line position shown on the vertical bar represents the water level. The lower part of the horizontal line is the water atmosphere and the upper part is the steam atmosphere. The water level and temperature detection sensor 6 installed inside the in-core instrumentation tube 7 is indicated by a triangle. A thick line sensor indicates that the water atmosphere is determined. The water level (in mm) of each group is displayed as text on the vertical bar. Moreover, it has shown that the 3rd sensor c from the top of the in-core instrumentation pipe | tube 7 shown by 4-6 of the 3rd group has failed. The horizontal bar displayed at the bottom of the screen is a slide bar, and the water level measurement value at the corresponding past time is displayed when the operator moves the cursor on the bar.

  Thus, according to the present embodiment, even when the temperature inside the reactor pressure vessel 1 is different, the water level can be accurately detected, and the soundness of the water level and the temperature detection sensor 6 can be evaluated.

  In this embodiment, the apparatus configuration is the same as that shown in FIG. However, as shown in FIG. 15, the measurement flow of the reactor water level and temperature is partially different from that shown in FIG. In addition, the same step number as FIG. 5 has shown the same processing content.

  The water level / temperature / failure determination device 18 collects data necessary for determination of the water level / temperature / failure by repeating the following control for all the water levels and the temperature detection sensors 6 according to a predetermined order. (Step S10).

  First, a temperature data collection command before energization of the target sensor 6 is output to the temperature measuring device 16 (step S20). The temperature measurement device 16 that has received the collection command inputs an output signal from the target sensor and sends it to the water level / temperature / failure determination device 18. The water level / temperature / failure determination device 18 stores the received temperature data from the sensor in a storage device (not shown) (step S30).

  Next, a command is output to the heater control device 17 to energize the heater wire 25 of the target sensor 6. The heater control device 17 increases the energization amount to the first preset current value built in (step S110). After energization for a predetermined time, the water level / temperature / failure determination device 18 outputs a temperature data collection command during energization to the temperature measurement device 16. The temperature measurement device 16 that has received this command inputs an output signal from the target sensor and sends it to the water level / temperature / failure determination device 18 (step S120). After storing the received temperature data from the sensor in a storage device (not shown), the water level / temperature / failure determination device 18 determines whether the surroundings of each water level and the temperature detection sensor 6 are in a steam atmosphere according to the collected temperature data. Is determined from the threshold table (step S130).

  And when it determines with a steam atmosphere, electricity supply is complete | finished and it transfers to the data collection of the following object sensor (step S140, S180).

  On the other hand, when it is determined that the atmosphere is not a steam atmosphere, in order to determine whether the atmosphere is a water atmosphere or a sensor failure, the heater control device is configured to energize at a second current value set higher than the first current value. A command is issued to 17. After energization with the second current value for a predetermined time by this command, the water level / temperature / failure determination device 18 outputs a temperature data collection command during energization to the temperature measurement device 16 (step S150). Then, according to the collected temperature data, it is determined based on the threshold value table whether each water level and the temperature detection sensor 6 is in a water atmosphere or is malfunctioning (step S160).

  FIG. 16 shows an example of current value control in this embodiment. In this example, when the steam atmosphere and the water atmosphere are determined, the energization amount is 0.5 A. Thereafter, when the water atmosphere and the failure are determined, the energization amount is increased to 2.0 A. By repeating the above control for all the water level and temperature detection sensors 6, the collection of data necessary for determination is completed. Thus, based on the result determined with respect to each water level and the temperature detection sensor 6, the water level height for each group is determined and displayed on the screen in the same procedure as in the first embodiment. .

  According to this embodiment, in a steam atmosphere in which the temperature of the heater wire 25 is likely to increase with energization, the current to the heater wire 25 can be suppressed to a small level, and disconnection of the heater wire 25 can be prevented. By increasing the current to the heater wire 25, it is possible to reliably determine whether it is in a water atmosphere or a failure.

  This embodiment is the same as the second embodiment. However, the temperature rise time constant is used to determine the steam atmosphere and the water atmosphere.

  FIG. 17 shows a flow of measuring the water level and temperature. As a condition for determining the steam atmosphere and the water atmosphere, the point of using the temperature rise time constant (step S130A) is different from the second embodiment. The threshold value table shown in FIG. 7 similar to that in the second embodiment can be used to determine the water atmosphere and the failure. According to this embodiment, it is possible to reduce the time required for determining the steam atmosphere that requires a relatively long time until the temperature is saturated.

  In this embodiment, as a failure detection of the water level and temperature detection sensor 6, in addition to a method using a temperature rise amount and a threshold table, a method based on measurement of the loop resistance and insulation resistance of the sensor is used in combination.

  FIG. 18 is a conceptual diagram showing the system configuration of this embodiment. A resistance measuring device 42 is additionally provided in the configuration of the first embodiment. Details of the resistance measuring device 42 are shown in FIG. Thermocouple wires 22 and 23 and heater lead wires 26 and 27 drawn out from the water level and temperature detection sensor 6 are branched from the cable 15 connected to the temperature measuring device 16 and the heater control device 17 to be inside the resistance measuring device 42. The switch 43 is connected. The switch 43 selects one of all the water level and temperature detection sensors 6 based on a command from the water level / temperature / failure determination device 18 and connects it to the ohmmeter 44. The ohmmeter 44 measures all inter-terminal resistances between a total of five cables obtained by adding the ground wire 45 to the thermocouple wires 22 and 23 and the heater lead wires 26 and 27, and the water level via the transmitter 46. Data is transmitted to the temperature / failure determination device 18. The water level / temperature / failure determination device 18 that has received the resistance data compares each resistance value with a predetermined determination value to determine a failure in the water level and the temperature detection sensor 6.

  According to the present embodiment, even in the case of the water level and the temperature detection sensor 6 determined to have failed because the temperature rise is small, only the heater lead wire is disconnected and the thermocouple strand is healthy. There is an advantage that the state can be detected and the thermometer can be used.

  In this embodiment, the reliability is improved by specifying the insertion position of the in-furnace instrumentation tube 7 incorporating the water level and temperature detection sensor 6 into the furnace.

  Although the overall system configuration is the same as that of the first embodiment, the in-core instrumentation tube 7 including the water level and temperature detection sensor 6 is adjacent to the outermost peripheral fuel of the reactor, as shown in FIG. It is arranged outside the outermost peripheral fuel. In the reactor core 3 of the nuclear reactor, the outermost peripheral fuel has a large effect of neutron leakage, usually a low-reactivity fuel is disposed, so that the output during operation is small, and the decay heat generated by the fuel after scram is There is a characteristic that it is relatively small compared to the central portion. Therefore, by arranging the in-core instrumentation tube 7 in such a manner, even if a situation in which the fuel is exposed occurs, the periphery of the in-core instrumentation tube 7 is the center of the core 3. Compared to the above, the temperature is relatively less likely to rise, and the period during which the water level and temperature can be measured can be lengthened.

  In this embodiment, in addition to the configuration of the fifth embodiment, an in-core instrumentation tube 7 having a built-in water level and temperature detection sensor 6 is also installed in the central portion and intermediate portion of the core 3.

  FIG. 21 shows the arrangement of the in-core instrumentation tube 7 inside the reactor pressure vessel 1. As shown in FIG. 21, the in-core instrumentation tube 7 including the water level and temperature detection sensor 6 is disposed not only in the core outer peripheral part but also in the core central part and the intermediate part. In combination with such an arrangement of the in-core instrumentation tube 7, the temperature data measured by the individual water level and the temperature detection sensor 6 or the failure sensor information is stored in time series, so that the temperature distribution change in the core 3 and It becomes possible to confirm the progress of sensor damage.

  FIG. 22 shows a display example of the three-dimensional temperature distribution inside the reactor pressure vessel 1. The three-dimensional temperature distribution is represented by a color-coded contour map, and a failed sensor is indicated by a cross. A slide bar is displayed at the bottom of the screen, and when the operator moves the cursor on the bar, the temperature distribution and failure sensor information of the corresponding past time are displayed.

As described above, according to the present embodiment, it is possible to visually grasp the three-dimensional temperature distribution in the furnace and the information of the failure sensor, and by displaying the temporal change, the temperature distribution change and the sensor breakage are displayed. Can be confirmed.

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel 2 ... Shroud 3 ... Core 4 ... Core indicator board 5 ... Upper lattice board 6 ... Water level and temperature detection sensor 7 ... Reactor insertion tube 8 ... Reactor instrument housing 9 ... Reactor instrumentation guide tube DESCRIPTION OF SYMBOLS 10, 11, 12 ... Water flow port 13 ... Cooling water 14 ... Stop cock 15 ... Thermocouple and heater cable 16 ... Temperature measuring device 17 ... Heater control device 18 ... Water level / temperature / failure judgment device 19 ... Storage device 20 ... Display Device 21 ... Sheath 22 ... Thermocouple + side strand 23 ... Thermocouple-side strand 24 ... Thermocouple 25 ... Heater wire 26, 27 ... Heater lead wire 28 ... Insulating material 29 ... Connector 30 ... Flow stop 31 ... Through Water port 32 ... opening 33 ... weld 34 ... neutron detector 35 ... scanning neutron detector guide tube 36 ... steam separator 37 ... steam dryer 38 ... steam condensers 39 and 40 ... differential pressure transmitter 41 ... fuel Aggregate 42 ... resistance measuring device 43 ... off Instead 44 ... resistance meter 45 ... ground wire 46 ... transmitting device

Claims (7)

A reactor water level and temperature measuring device for detecting a reactor water level from a temperature measured by the thermocouple by installing a plurality of thermocouples inside a reactor pressure vessel,
An in-core instrument housing welded to the bottom of the pressure vessel;
An in-core instrumentation guide tube disposed between the upper part of the in-core instrument housing and the core support plate;
An in-core instrument tube inserted into the in-core instrument housing and the in-core instrument guide tube;
A water level and temperature detection sensor comprising thermocouples and heater wires installed at a plurality of height positions inside the in-core instrumentation tube;
A temperature measuring device for measuring the temperature of the thermocouple;
A heater control device for controlling a current to the heater wire;
A storage device storing a threshold table for associating a thermocouple temperature before energizing the heater wire and a thermocouple temperature increase amount when energizing the heater with a steam atmosphere, a water atmosphere, and a sensor failure;
Applying the thermocouple temperature before the heater energization measured by the temperature measuring device and the temperature rise amount at the time of the heater energization to the threshold table, whether the water level and the surroundings of the temperature detection sensor are a steam atmosphere or a water atmosphere, Alternatively, a water level / temperature / failure determination device that determines whether a sensor has failed and generates information on the water level, temperature, and sensor failure in the reactor based on these data, and
With the water level, temperature, and a display device for displaying fault information,
The water level / temperature / failure determination device holds a first current set value for determining a steam atmosphere and other than the steam atmosphere, and a second current set value larger than the first set value,
As a result of energizing the heater wire with the first current setting value, energizing the heater wire with the second current setting value and determining a water atmosphere and a sensor failure only when it is determined that the atmosphere is not a steam atmosphere. Reactor water level and temperature measuring device. In the reactor water level and temperature measuring device according to claim 1,
A reactor water level and temperature measuring device comprising a flow stop for suppressing the flow of a coolant around the water level and temperature detection sensor. In the reactor water level and temperature measuring device according to claim 1,
A resistance measuring device for measuring a resistance between a thermocouple wire drawn from the water level and temperature detection sensor, a heater lead wire and a ground wire;
Reactor water level and temperature characterized in that a resistance value measured by the resistance measuring device is compared with a judgment value held in the water level / temperature / failure judgment device to determine and display a failure in the water level and temperature detection sensor. Measuring device. In the reactor water level and temperature measuring device according to claim 1,
A reactor water level and temperature measuring device, wherein the water level and the installation height of the temperature detection sensor are arranged so as to interpolate each other inside a plurality of in-core instrumentation tubes. In the reactor water level and temperature measuring device according to claim 1,
A reactor water level and temperature measuring device comprising a storage device for storing detected reactor water level, temperature, and sensor failure data in time series. In the reactor water level and temperature measuring device according to claim 1,
The furnace instrumentation tube is inserted into the furnace instrumentation housing and furnace instrumentation guide tube is disposed outside the adjacent or outermost fuel outermost fuel reactor atoms, wherein the kite Reactor water level and temperature measuring device. In the reactor water level and temperature measuring device according to claim 6,
In addition to the in-core instrumentation tube located adjacent to the outermost periphery fuel or at a position outside the outermost periphery fuel, an in-core instrumentation tube is disposed at a position other than the above, and a plurality of heights inside the in-reactor instrumentation pipe are arranged. A reactor water level and temperature measuring device comprising a water level and temperature detection sensor having a thermocouple at a vertical position.

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